U.S. Pat. No. 4,249,330 to Chioffe discloses a medical pendant which enables an observer to view microfilm. The medical pendant has an interior, hollow chamber with the microfilm mounted at one axial end of the chamber and a magnifying lens mounted at the other axial end of the chamber. The chamber is not waterproof and the placement of the film relative to the lens varies depending upon certain manufacturing characteristics. U.S. Pat. No. 4,920,672 to Scott, Jr. et. al., discloses a medical pendant with enhanced visibility. This device enables a user to view microfilm data. The data is located in an end cap which is threadably mounted into an interior, cylindrical hollow chamber. A magnifying lens is mounted in the chamber at an opposite axial end.
Both view scopes are not waterproof and the distance between the lens and the microfilm is subject to variation due to manufacturing tolerances and errors.